In my British patent specification No. 1541423, which corresponds to U.S. Pat. No. 4110063, there is described such a solid-fuel effect gas fire which comprises a mass of particulate refractory material in an open-topped tray, a plurality of refractory bodies, shaped and coloured to simulate solid fuel, arranged in a heap on the top of the particulate refractory material, means for supplying a gaseous fuel into the mass of particulate refractory material so that the gaseous fuel percolates upwardly through the mass of particulate refractory material into spaces between the bodies, and at least one air passage for providing extra combustion air to the gaseous fuel flowing to only some of the spaces between the bodies so that, in use, the gaseous fuel provided with the extra combustion air from said passage burns with a non-luminous flame and that without the extra combustion air burns with a luminous flame thereby realistically simulating a solid-fuel effect fire.
In use, I have found that the appearance of these fires is very realistic and from a distance it is difficult to determine whether or not the fire is a solid-fuel fire. This is due to the fact that, when the gas fire is in operation, the gas burns to produce both luminous and nonluminous flames, as are present in a solid-fuel fire.
I have found that, in use, the gases of combustion of the previously described solid-fuel effect gas fire have a CO.sub.2 to CO ratio of between 1:0.02 and 1:0.01. Clearly the operating combustion efficiency of the fire would be improved if this ratio of CO.sub.2 to CO could be changed to reduce the CO level still further. An increase in combustion efficiency would result in flames of still higher temperature and this would lead either to a greater heat output from the fire for the same quantity of gaseous fuel or the same heat output could be obtained with a reduction in the gaseous fuel which is used.